SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c79e450e6fbb0a051d45c29a83ec38da9f02bed5789e1cceff465a297a7d3c1d' 
  AND token = 'vfPQXFWC/CgggIvR1eOze4RPW4afeOBjdYJOvhwG/Hw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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