SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f3f42ea462a6e5a9a02fd554660af586329ad204d8b8678f33343a46a4ccea5' 
  AND token = 'GRZk0eez4KhnHICRVGYi7S9b9OXSehtTPbR0EIP32qE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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