SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f820515607ef0f1725f4394ef7f3569290b6db7a8224ecd775778b0f9d3a9f78' 
  AND token = 'G6/DuXoiPyhilt/5laPk7PWEXS2VEaRstLhDCmycTPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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