SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18c8c5d709e8870d3b75ad0438cd7d75984b841f678b2b888ed695c7a7b09f92' 
  AND token = '4wYMt7TBJeKwKFVkTKyftP63hElObgqzLZI2omi3uf4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

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