SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '848b175573b9ade3d77aca78969dffbfe47378c18302ccb59a69da7d442b133c' 
  AND token = 'NGdwvhLsf1oGMxf3VFutwQ/y+uLi2aaPpyw2SqR3jIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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