SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2a6e86603ed73cd0ce2da9e578dd3b3fa213733c320d1ecf58f3bf3dd4635a1' 
  AND token = 'L8M5ONZ1vb9LuooiJn3rr0PJJzQ/WJkCXbZvFZkEj8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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