SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4ef78048a3929a554cf11a65d1730447946e69569196a56f279b22c02179212' 
  AND token = 'QbAWlOgsiAD9ePikyDLn/WGxYqG42B92TvXQ1vgy2gI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables