SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91ca16f7538951d66f101c67a3aafa25d4e28f99fc893fb0ad5813fcad5e7ccb' 
  AND token = 'PC3vJrVGXWWBR5PEZ9RD+OCaa4B+IL9pH5ovnNaq5Gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

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