SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bea1ed3ae00c1a8917dd87eefafd1f7ad5c4fc45e59475d1aec74296afb30e8f' 
  AND token = 'FzjLbAxERBjf6qscGIPLT1ySVOO5xBmhqxgrQFDsIg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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