SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b3758fd2ccf2e37783e2f32630226da7152c54bfb43053a9e271891ec3d7917' 
  AND token = 'e0vnaWeZMyBZl1ila+Glu6iMRWnsjbEHnoud0B02yNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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