SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c843c39335d13bae4839e152a7be21b7278084c2767591f6e754f9d10899b344' 
  AND token = 'xvJ1O8YuPjwZRAIKpWZG+IQCE15ww6cK5ny9QzEPrI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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