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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ea31f7b2fbdfe1aef8632b4377ad5942a29b7398f364b3328c01ddd3d2ba97a5' 
  AND token = 'Ab/3cWrm6re/6+W30r0P5MGQSEeHLpsVkHqbSFHxyec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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