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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '90a37a02a464074462920980a466c3cf338c394f14ee4d4dba1e5d1f1eaec704' 
  AND token = 'lC/pMnICl+AeL806demxS7jb5KKW3UZeXijvO4tzhqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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