SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ebf3617e3df6d1aff069f06f0baccafc458f8192c760b050182f028d58e3f3d' 
  AND token = 'K+Y+FPYGCUM3AS/Qh4YcWQNsw4KSkG1nX72hRj9o3Pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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