SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3b4b5d7fbd49d617cb3bad801f161ce962e315dd19755eb92b6cf75d1da55ad' 
  AND token = 'Cm1GnN9G4IdFFNYOV0Hs0LIRmEOm3sA+msCTwcjeRg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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