SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9be82b66ffff503a9ca29412bdf26197609f5aca12d01f0ece6e338bfef6e83' 
  AND token = 'u4SmufCJExJTpfQn7EzWtohwmbZZhe4pV28dTsFCuBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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