SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd01a4a865b10047df3d291a3e576d74955e0851dffbd3f4df60e88b2d882d0b6' 
  AND token = 'xULkok5JfsEmvBreI2GWdg+PluT9iy3xcuRu4Ds0kX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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