SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39cd43fdc393de1af170616d6ce3e6bc77394eb2d66881c39657247feda0107a' 
  AND token = 'VslPc3c3IL1prOZZ6KJjPuz3ooaDfSP9bGGik+aDP+0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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