SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6b7641d2983b2a7a535a656cf363a16bdddc86faa86d950ade9eaa1fd877be6' 
  AND token = 'UUpel0bfyMYC5nl9zAh7Zt/wa4g5g04/+2w+JXvtHJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

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