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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b6b2b27c08dddcdfeac2eacf33fdb8246cdc6a7d51eb6a7660a0a120e13da209' 
  AND token = 'G6QQ9dlV5tYmVzFiWTf7xeBvLIZdKLqbOi8AU4UuVJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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