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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e3702737b9888b8a564dd8a77e7540d41d2afd5dda17c161c3b6c9ca568186b5' 
  AND token = 'Jbrghfvp67Ls+si4LsofGXHdqh245tTCNPonJ+SA35A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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