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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '81c4df3f5b212010300b97ff812c4b22e8c73a073ace6d89f20ca56ad5624ee7' 
  AND token = '7rO8rvaGl7L2TWYGxwssgCxj0A2QLsKuQFxEkkF2UPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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