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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '56f48ec78be8bda1f6f8ef18c4a8046ef0d673d8b9ffd4b72216dcc0756678e3' 
  AND token = 'U6vnGBcqMDCtj6IEYrODvx30Q1oYJlBrplgTfFQN2ys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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