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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebf94f67ea83ed86ceb05352ee1e8a5840cd75ff33a63e1a0969dd8d9c374e25' 
  AND token = 'QSAkkeY9kqO/1XoweLyiN5eZTaiBdMT1LBXnZdCdrRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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