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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '657fde4cea0d7a648dc40a256148abc684022256ce70568d13f09c29a80a078e' 
  AND token = '5fJVfUNwUOy2G2DIPHtRmStu5RVjO1kspHAJb265o3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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