SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c37cc574651da054ab8f1a5a7aeb8d9ce425641e50616bed8bdd4310a9d3a1b5' 
  AND token = 'SPcxRniuBCeKknSxXLPvHULeDjN49hm9HOZpldtvVCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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