SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '324e818f9c21293d64a45fdd7b2c20ce56a4015d0c6460e548e5e0ab31d4ea95' 
  AND token = 'sB3aI/cyzn17z3yNt4mezCb4DShXrngs23tu0baikFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}