SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '157bc15e2834308773b9b804262a17e9f82c70cf5fbccc711dbdd9e53c234c7d' 
  AND token = 'ldW2NNE876PyrvEK2Naju+baufbG8Y2ZotdXmLTkmgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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