SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6438a66ddf98a7902c64cd38c2862c18c77bf60fd2094b609158326d65e9ff23' 
  AND token = 'i7fznnGy/shY5nirxkUgxVrU1fYI+9TzxDEZLUBFG8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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