SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a263ed638e8906fdb9711b877d9f8ed03c429706af5fa610aae331f6a7f94c' 
  AND token = 'SFF/RhkI/LjYgweEkkgD0hpJ/mYd+hJJbsZKtwcv4+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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