SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b847a8d09a14faf65f845faa173117e7d2e194d6551b6889cfef2eecc97a3ec' 
  AND token = 'AHEtUv7TYjzIx4RYSpE3ytMavM6IBguFMKSY+2+rgbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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