SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8157347047bf7502f38bc3e4e07b07881938f5ec12ee3e00bf72bce6b557d329' 
  AND token = 'MKJEGw2OOkda2D4PMz21jt/MhdUZUOrKiBBAlCUIpBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

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