SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c992e3a865cb340438b0ccbf3a05fa6639d6ae832cb03fea8237bd7f63d4b68c' 
  AND token = 'GLdulVZyXnPcYd2Ng+Gr3jeqxZCnnRrHofi5ygAGuD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}