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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b6bb1a59d233bcde8ccee961b49bb972842117b3c06cc671cd6ae88f6d1bb0f0' 
  AND token = 'O2MIEFX1LVzB9Jv3EcAdzXz7pyq+tfxqmrYmoRqPfZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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