SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1e372bc214d2640faa7e84ed0b5df512adc70d15d6192eeeb6594f090328e9c' 
  AND token = '6I596iYsXOm1HqUJDegcbCcinuLJeQ/ML+bUd0twjpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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