SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d4842abecb1835d09e53a87e6d61c4670a3f65a9cc285510e414a80aa20f23a' 
  AND token = '527MDlyPGaI22gUgKs5Xc5bbFYLlsMEaUyW+tyjeYuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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