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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5f36f9fc604786bba75c72fed49eff67a33aea3888c9f19a023236d38442e7b0' 
  AND token = '3zfFs2g2ippa0S8p5v/fj6k1EnXS4utenqwiW3cz7L8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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