SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fca79cf3ba202d981fc91aa391692658a75cdf1ecc11b05914a096aa3f982e4b' 
  AND token = 'rjMAo+Mw6i+veCTNK6aLzkomCHxkvjvZiLAIjtrMCfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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