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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '55f9747e56cbc51fcb5da35b04a8b94a058998b56c35b4e46ad3091b03cf5bb5' 
  AND token = '2GPsutLyu8KSdXp/vgqbfHS/ECPh0Je0ct4rmswDlT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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