SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3191a1c79c8925f6c3428be308537aeb95187de1cd024193fe9f4d2aedb0e8d1' 
  AND token = 'KyPuEuFl62u2PU3jEaTHB9VM4mCrxIaOUFhYvUAmYrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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