SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4625baf352782a0148b62182682f9bab2d6a73320efcbe3e54504227127fb4c8' 
  AND token = 'MkZ5XhrOo7RtAzR+XTBeCFvVuGxkIxmvGpQFQhfl4cg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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