SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5392a5c3ede83ed69fa9931354d69f7b1b67675c19374a6f6bde083caa705329' 
  AND token = 'gGwhPlG4frf7oxOKwgNd90dEPjvkaHE+pvGijQxVzAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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