SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4875d607b325bace5eec2622960f5fb51bef700f9cf440d0bff00fd61147667b' 
  AND token = 'smV6Fi7AolwUzo17Fn1hxNffJSRky+tj/9hV9lTaDTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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