SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '93d3f379ef5039f333605e6df42f0892489a747faf29890057ba4d35e7fa8bda' 
  AND token = 'stNofoEJ27NAFzGn56kPxoivBCFd9DFpPf9Nmshpcr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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