SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b81e0e9ef84fc46cecdf77691f6266140009856d4bfc1a7466ffd90e486427a' 
  AND token = 'xm3mIFXnidGxrh5qhYrjc56vr45KGtUENxjzwCJIoKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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