SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e421efeb8d545a4f39fa2938d28f41a1d13eb78be63c9980c3fb52ec0931d6da' 
  AND token = '0gcus0gQiTBL8EQ+X5uSMJhmVKSlUdvBkl+rAYQ34Rw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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