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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a42f8f7fc44976d1fac259d3cfd2254eabc780c0536eac76e91301426abb6e6' 
  AND token = 'R5+Uy+Pj4gsc7Bxdfouv7D4QIN5Igw9wAn4FhcrHCwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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