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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c8fe8cbe9a2493cdf43a8d10de99fd211091ef354a0778a17b17804b88b3eb0f' 
  AND token = 'cE0aY5b2SWINj7ISnrvGW1JukXeUDxxsa3Jt4Suo9ZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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