SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0f634354bb478dd511c704115dec1b7e5bd0df9ff81211a34744d7835f94a29' 
  AND token = 'RvvmziapnKrlSdRepqSvfVi8oqMayzEr+TkIZ8czsG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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