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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6be455d7e91505f34cba6ccdb82cbc4a4958b37d0cc3800ed17bd405f7be550' 
  AND token = 'Dp2/ZyYz8VwuVjeu/RRHkBCoEba1TXw4wPkXK0TpCrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}