SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd83fb53cbaddf6a40f2478de8abc7f4582a4bff833447c1bbdf142593027015a' 
  AND token = 'qm1Nw2SVxQa+ujKHIEZPMgvi5dzPpRKjyzS7WRK/F3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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