SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e647a7514b137918a6623d864a28d690637f7a9b26d97e6e8a3ce68bd4d4b3af' 
  AND token = '5ZZhtxoZnb14Pi8cy6sGbELmGAQF80fc1at2z1Ng/wI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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