SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '120f89c6ce8fe81936276535683ea73a34758707dbbe883e7dc9026ef7147758' 
  AND token = 'lY37mOSppVoSNozTwXZtx17wQ2FnhkdeClDfIp89y5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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