SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e75bc67981736a5a4eb702ec1abe3f5241eb096cef58c14c0136b0309c855371' 
  AND token = 'WOVlqchQTs+nQIjriOtcWLrVJRRddM6pTrpuIpw/tPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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