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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '89071ae7e1b1783a421e9997827feea886b1f100e3d18bbe87274818236e8882' 
  AND token = 'Yz3qZnTwZ0kZJS8Q9HWfbBsZ2Gcj4uMxgJhyJ0kQcl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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