SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a5794a38a46ed8c2aa555f583af98ad44cdcae2e4663b4b4f1047cf0203bb0f9' 
  AND token = 'U4gq1ieNwim9WdIb6/ZZVJjbvV497gZK6ajg+rSChOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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