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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bc6bbcbe398bc3e5e641e2e838cd91f3e311899c512ee1a057e7d279232ccf23' 
  AND token = 'eexux5MmAQcfenXzT/mwy52fGENvNEceNWhkHo1X5lk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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