SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cade71928dc101c3ded32ef6ddafebfc81e816dba594f8a1ab84732f9973ca7' 
  AND token = 'lgSiZVkqzgG28sxoTd62J31RJglzO615mpRlGMQpDDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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