SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '592af90b33e577f643a17752f3896670d5a47b99ebaa6a24965dd0e588b9de30' 
  AND token = 'n6P3/o6ExNQkTN/wP6ta1JrELsk8es+zEU3SBzeVsLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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