SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ea5d324bc0e43e677cf6e528fe620c158312f18b091f78a34250fe97c64bc46' 
  AND token = '+51Jymjk5FCzbOh/t3ZffdVgwZhCGy3zzwTJkFnfsh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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