SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a46fe8ac57b821b5321a7f6b433a9197b8f191a214b435c5a525df4279eaa6c' 
  AND token = '9JSn8PmxHFHOFIPYDPHNKBtLFa6zCeSqWQVzEt/DCHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}