SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fcd59f90eea03a7078850fa10b794efdae9e5d434783e9910ad0a934b9ed248' 
  AND token = 'RN6f/Hc3pMnLH0Cm7ENfkmV2y/L0NNcWx3ynKPXaspM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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