SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dacbb8e387a503596b910e8905c9fd776abd5d4322a398f2fc2f441a96d96fee' 
  AND token = '4Vy1xxoNmxH7Y7y1Rs/NOBdTCgAP5CryZLbxiOmFsE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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