SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82fd91982080bec8c676d06e2699afb7c098cd69239fe3852c4fc043a4387878' 
  AND token = 'dfET5ulHCAzQJMjdRCcOzul6TQ00oOQWkVcDrsR3MG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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