SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18f6645017af141f3d25c945b27e8bfdcc48208f2c19bb8705dad0b8c4658159' 
  AND token = 'c324qxXAnUaZdkQfD7JLSHcoF7i+AldIv4SEwJ4V4EA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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