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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6fa68fb65d48bd62adf1b4e34ccf0b40f38037062d3d82bfe914827ba48c9d1' 
  AND token = 'dM0O+8VBveEGtv12IqNUMjuUkSi+TOR0+qhx0vc9rnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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