SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '688a00ed58a77d5e369218c971d07c4c7bda3b11bb9db81f39a2ff775a965ccf' 
  AND token = 'QVWynAgI68j5VrrbYhM/CzABsdr/2vHY/hrBOzZ0x7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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