SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d098d2c6bb332ee5224aab11f3f3e8b0f7792d72900b0edc2981f4a96f91a44' 
  AND token = 'mfwGoiTh5DLQp3ZeEVWDwENjYoZvAj1JNVweVXHFzBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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