SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f7a254142835abd54585a0f7335350055375cf277bd00a3b7dfee7c7369abb3' 
  AND token = 'rBW4fZifMiDhZg07DIl+PhPVAUkjhtBZERW46FZLRmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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