SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e63eb85d1e344a83ad1e9f7488385a176909dca77afd853ba882429760618315' 
  AND token = 'dNehEAGzURasWGYJidH4A6aYbfeMK/Qb1qWCHES3vAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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